F-substituted carbonate apatite for promoting bone formation

Fluoride (F)-substituted type-B carbonate-containing hydroxyapatites (CHAPs) were prepared as bone substitutes with a F-releasing ability. The F ^- contents in the F-substituted CHAPs were 16-22 times larger than that in normal adult human bones. The carbonate contents in the F-substituted CHAPs corresponded to that in human bones. The F-substituted CHAPs released F^- in an acetic acid - sodium acetate buffer at pH 4.9; within only 3 h, the F^- concentration in the buffer increased to more than 63.9 μg L^-1, which was 1.5^- 8.9 times higher than that in a body fluid of normal adult humans. Although the F^- concentration rapidly decreased probably due to the precipitation of a certain phase containing F^-, the F-substituted CHAPs exhibited the ability to increase the F^- concentration in a body fluid by bone resorption. Therefore, it is expected that the F-substituted CHAPs will be feasible as a F-releasing material for promoting bone formation.